A conventional electric motor drive device used in a drive device of an electric car and a hybrid vehicle is disclosed in a Japanese Unexamined Patent Publication No. 2006-22879 (patent document 1). The electric motor drive device disclosed in the patent document 1 includes an electric motor, a first speed reducing part to reduce speed of an output of the electric motor with a high speed reduction ratio, a second speed reducing part to reduce the speed of the output of the electric motor with a low speed reduction ratio, and first and second intermittent means provided in the first and second speed reducing parts, respectively, to selectively disconnect the first or second speed reducing parts. The electric motor drive device is provided with a first shaft to transmit output torque of the electric motor, and a second shaft arranged parallel to the first shaft, and the first speed reducing part has a first gear arranged in the first shaft in an integrally rotatable manner, and a second gear arranged in the second shaft in a relatively rotatable manner. In addition, the second speed reducing part has a third gear arranged in the first shaft in a relatively rotatable manner, and a fourth gear arranged in the second shaft in an integrally rotatable manner. Thus, the first intermittent means is a two-way overrunning clutch to make a connection/disconnection between the second shaft and the second gear, and the second intermittent means is a multiplate friction clutch to make a connection/disconnection between the first shaft and the third gear.